The year 2023 was another sad year in US environmental history with 21 more species being declared extinct.

Among the casualties were eight bird species, including the poignant demise of the Kauaʻi ʻōʻō, a striking black and yellow bird distinguished by its glossy plumage and haunting melody. Once the last surviving member of the Hawaiian honeyeaters, the Kauaʻi ʻōʻō was officially declared extinct.

The plight of the Kauaʻi ʻōʻō epitomises a broader trend, as evidenced by the removal of 21 species from the endangered species list by the US Fish and Wildlife Service in 2023. These species, including the little Mariana fruit bat and the bridled white-eye, had tragically vanished from the wild, leaving behind a void that underscores the accelerating extinction crisis fuelled by climate change and habitat destruction.

While the delisting did not come as a surprise to biologists and conservationists, it served as a sobering wake-up call to the urgency of addressing the interconnected challenges of biodiversity loss and climate change.

“It’s a horrible tragedy,” said the ecologist and author Carl Safina. “And I think it is a breach of our moral guardrails.”

In Hawaii, where the loss of biodiversity resonates most acutely, eight of the delisted species were endemic forest birds, their dwindling populations imperilled by avian malaria transmitted by invasive mosquitoes and rampant habitat loss.

Rachel Kingsley, an outreach associate with the Maui Forest Bird Recovery Project, underscores the compounding impacts of the climate crisis on Hawaii’s delicate ecosystems.

“Many of the same threats faced by the birds that were recently declared extinct are the same ones threatening our forest birds now,” Kingsley said. “Within the last handful of years, the threat of malaria has really increased dramatically.”

Efforts to combat avian malaria, such as releasing mosquitoes carrying a bacterium to suppress reproduction, are undermined by rising temperatures that expand the mosquitoes’ range, encroaching upon higher elevations and further imperilling forest bird populations.

“Unfortunately, it seems like the fast forward button kind of got pushed down on us,” said Kingsley.

Moreover, global heating has exacerbated extreme weather events, exacerbating drought and wildfire risks, which in turn threaten Hawaii’s forest birds. The spectre of extinction looms ominously, as evidenced by a devastating wildfire that encroached upon a conservation centre housing some of the world’s rarest birds, including the critically endangered ʻakikiki, considered the most endangered bird in the US.

For scientists like Jim Jacobi, a biologist with the Pacific Island Ecosystems Research Center, bearing witness to the decline of these species is a profound and devastating responsibility. Jacobi’s nearly 50-year career has intersected with the vanishing song of at least four birds now considered extinct, including the Kauaʻi ʻōʻō.

“I still get goosebumps – the hair in the back of my neck stands up when I think about it,” he said. He and two other researchers had hiked out to a remote forest in Kauai when they heard it. “That Oo’oo – oo-auh sound.

“It was just amazing – very flute-like,” he recalled. He immediately turned on his recorder to capture the song.

His poignant recollection of encountering the elusive bird serves as a poignant testament to the loss of biodiversity and cultural heritage.

“I thought, wow, this is fantastic!” Sincock said. Almost immediately, he deflated. The ʻōʻō had been drawn to a recording of its own voice – thinking it was another bird. “It came because it thought it heard something that it probably hadn’t heard for a long time – another of its kind,” he said. This bird was perhaps the last of his species, singing for a mate that would never come.

The extinction of the Kauaʻi ʻōʻō symbolises the loss of an entire avian family, underscoring the irreparable damage wrought by human activity on Hawaii’s unique ecosystems.

Jonee Peters, executive director of the Conservation Council for Hawaii, reflects on the cultural significance of these birds, whose grand tail feathers once adorned the cloaks of Hawaiian royalty—a tradition emblematic of a bygone era of symbiosis between humans and nature.

“What makes us Hawai’ian is the collective experiences of ourselves and of our ancestors,” said Noah Gomes, a native bird expert and historian based in Hilo, Hawaii. “We’re losing something of ourselves when these birds disappear.”

The federal government’s decision to delist nearly two dozen species, finalised in 2023, has galvanised calls for enhanced conservation efforts and strengthened legislation to protect endangered species.

“The news just made me so sad,” said Tierra Curry, a conservation biologist with the Center for Biological Diversity. “I had all these feelings back then and I needed to process them.”

Conservationists like Curry advocate for increased funding and resources to bolster the efficacy of the Endangered Species Act (ESA), which has faltered in the face of rapid biodiversity loss exacerbated by climate change and habitat destruction.

Indeed, the efficacy of the ESA has come under renewed scrutiny amid escalating threats to biodiversity. Species like the flat pigtoe mussel, afforded ESA protections only after the precipitous decline of its population, underscore the urgent need for proactive conservation measures. However, inadequate funding and resources have hindered recovery efforts, leaving many species teetering on the brink of extinction.

While success stories like the recovery of the bald eagle attest to the ESA’s potential, the current biodiversity crisis demands a paradigm shift in conservation efforts.

“But in some ways, the ESA is like having an emergency room and intensive care unit, without providing regular immunizations and check-ups,” said Safina.

The scope of the extinction crisis, he said, “is completely overwhelming to the capacity of the human mind to actually know and understand”.

With the climate crisis exacerbating deforestation and habitat loss, urgent action is imperative to safeguard the rich tapestry of life on Earth. As conservationist Carl Safina aptly observes, the accelerating pace of species extinction is a sobering reminder of the urgent need for concerted action to protect and preserve our planet’s biodiversity for future generations.

“And so the endeavour of stopping this crisis becomes more of a religious kind of experience than a scientific one, in a sense, more moral than practical.”